The present invention relates in general to power generating systems and more particularly to temperature sensing for controlling the cooling of inlet airflow to combustion turbine power generators.
An electrical power generator converts mechanical energy into electrical energy. A typical electrical power generator includes a stator and a rotor that rotates within the stator to thereby generate electricity. The rotor, in turn, is mounted to a shaft that drives the rotor. Various mechanical devices may be used to drive the shaft, such as a combustion turbine.
In a conventional configuration, the combustion turbine comprises a compressor to draw in and compress a gas, such as air, for example. A plurality of inlet guide vanes may regulate the inlet airflow into the compressor. The combustion turbine may also comprise a combustor or heat source that adds energy to the compressed gas and a turbine to extract power from a resulting heated gas expansion. In such a generator, the extracted power is used to drive the shaft, which rotates the rotor within the stator to generate electricity.
The capacity or power output of the combustion turbine may be increased if air drawn in by the compressor has a relatively lower temperature. Accordingly, cooling the ambient, or inlet, airflow before it is drawn into the combustion turbine can be a cost effective way to increase the capacity of the combustion turbine. One approach to cooling the inlet air is with a direct refrigeration-cooling system in which ambient air is cooled using conventional refrigeration devices and techniques. One drawback to the direct refrigeration-cooling system, however, is parasitic power loss. This is due to the relatively large power drain needed to power a refrigerator unit. According to some estimates, the parasitic power loss may be as much as thirty percent (30%) of the increased power output of the turbine power generator.